The Effects of Uranium on the Structure of Iron Phosphate Glasses


Because of their high chemical durability and waste loading capacity, iron phosphate glasses are a natural candidate for a nuclear waste disposal medium. We have studied the effects of uranium on the structure of iron phosphate glasses with both neutron and high-energy x-ray of neutron which is correlationsdiffraction. The results scattering, mostly sensitive to pair involving light atoms i.e. 0-0, Fe-O and P-O, indicate the main structural features of the base glass are largely unaffected by the addition of U0 2. The nearest-neighborbour P-O, Fe-O and 0-O peaks remain at the same position in real space and their intensities scale approximately with concentration. These findings are consistent with earlier results using Raman scattering and EXAFS on the Fe-K edge, where in both cases the spectra remain similar to the base glass. The results of high-energy x-ray scattering, which is sensitive to correlations involving the heavier atoms and thus complements the neutron measurements, are also consistent with the overall picture of uranium occupying interstitial sites in the relatively undisturbed base glass structure. Combining the neutron and x-ray data for a 10 mol% U0 2 glass suggests the intriguing possibility of a U6+ uranyl ion configuration although further work is needed to establish the precise local structure and valence state of uranium in these glasses.


Materials Science and Engineering

Second Department


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Article - Conference proceedings

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© 1998 Materials Research Society, All rights reserved.

Publication Date

01 Aug 1998

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